1H-Pyrazole

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Alexander F. Khlebnikov - One of the best experts on this subject based on the ideXlab platform.

  • fe ii catalyzed isomerization of 5 chloroisoxazoles to 2h azirine 2 carbonyl chlorides as a key stage in the synthesis of pyrazole nitrogen heterocycle dyads
    Journal of Organic Chemistry, 2018
    Co-Authors: Kirill I Mikhailov, Ekaterina E. Galenko, Mikhail S. Novikov, Alexey V. Galenko, Alexander Yu. Ivanov, Galina L. Starova, Alexander F. Khlebnikov
    Abstract:

    2-(1H-Pyrazol-1-ylcarbonyl)-2H-azirines were synthesized by in situ trapping of 2H-azirine-2-carbonyl chlorides, generated by Fe(II)-catalyzed isomerization of 5-chloroisoxazoles, with pyrazoles. According to DFT calculations, the selectivity of nucleophilic substitution at the carbonyl group of 2H-azirine-2-carbonyl chloride by a pyrazole nucleophile, which is a mixture of two tautomers, is controlled by thermodynamic factors. 2-(1H-Pyrazol-1-ylcarbonyl)-2H-azirines are excellent precursors for the preparation of two other pyrazole–nitrogen heterocycle dyads: 5-(1H-pyrazol-1-yl)oxazoles by photolysis and 1-(1H-pyrrol-2-ylcarbonyl)-1H-Pyrazoles by a Ni(II)-catalyzed reaction with 1,3-dicarbonyl compounds. 5-(1H-Pyrazol-1-yl)oxazoles show strong emission in acetonitrile at 360–410 nm with high quantum yields.

  • Fe(II)-Catalyzed Isomerization of 5‑Chloroisoxazoles to 2H‑Azirine-2-carbonyl Chlorides as a Key Stage in the Synthesis of Pyrazole–Nitrogen Heterocycle Dyads
    2018
    Co-Authors: Kirill I. Mikhailov, Ekaterina E. Galenko, Mikhail S. Novikov, Alexey V. Galenko, Alexander Yu. Ivanov, Galina L. Starova, Alexander F. Khlebnikov
    Abstract:

    2-(1H-Pyrazol-1-ylcarbonyl)-2H-azirines were synthesized by in situ trapping of 2H-azirine-2-carbonyl chlorides, generated by Fe­(II)-catalyzed isomerization of 5-chloroisoxazoles, with pyrazoles. According to DFT calculations, the selectivity of nucleophilic substitution at the carbonyl group of 2H-azirine-2-carbonyl chloride by a pyrazole nucleophile, which is a mixture of two tautomers, is controlled by thermodynamic factors. 2-(1H-Pyrazol-1-ylcarbonyl)-2H-azirines are excellent precursors for the preparation of two other pyrazole–nitrogen heterocycle dyads: 5-(1H-pyrazol-1-yl)­oxazoles by photolysis and 1-(1H-pyrrol-2-ylcarbonyl)-1H-Pyrazoles by a Ni­(II)-catalyzed reaction with 1,3-dicarbonyl compounds. 5-(1H-Pyrazol-1-yl)­oxazoles show strong emission in acetonitrile at 360–410 nm with high quantum yields

Ayoob Bazgir - One of the best experts on this subject based on the ideXlab platform.

Kirill I Mikhailov - One of the best experts on this subject based on the ideXlab platform.

  • fe ii catalyzed isomerization of 5 chloroisoxazoles to 2h azirine 2 carbonyl chlorides as a key stage in the synthesis of pyrazole nitrogen heterocycle dyads
    Journal of Organic Chemistry, 2018
    Co-Authors: Kirill I Mikhailov, Ekaterina E. Galenko, Mikhail S. Novikov, Alexey V. Galenko, Alexander Yu. Ivanov, Galina L. Starova, Alexander F. Khlebnikov
    Abstract:

    2-(1H-Pyrazol-1-ylcarbonyl)-2H-azirines were synthesized by in situ trapping of 2H-azirine-2-carbonyl chlorides, generated by Fe(II)-catalyzed isomerization of 5-chloroisoxazoles, with pyrazoles. According to DFT calculations, the selectivity of nucleophilic substitution at the carbonyl group of 2H-azirine-2-carbonyl chloride by a pyrazole nucleophile, which is a mixture of two tautomers, is controlled by thermodynamic factors. 2-(1H-Pyrazol-1-ylcarbonyl)-2H-azirines are excellent precursors for the preparation of two other pyrazole–nitrogen heterocycle dyads: 5-(1H-pyrazol-1-yl)oxazoles by photolysis and 1-(1H-pyrrol-2-ylcarbonyl)-1H-Pyrazoles by a Ni(II)-catalyzed reaction with 1,3-dicarbonyl compounds. 5-(1H-Pyrazol-1-yl)oxazoles show strong emission in acetonitrile at 360–410 nm with high quantum yields.

Ramin Ghahremanzadeh - One of the best experts on this subject based on the ideXlab platform.

Gabriele Murineddu - One of the best experts on this subject based on the ideXlab platform.

  • tricyclic pyrazoles part 8 synthesis biological evaluation and modelling of tricyclic pyrazole carboxamides as potential cb2 receptor ligands with antagonist inverse agonist properties
    European Journal of Medicinal Chemistry, 2016
    Co-Authors: Valeria Deiana, Maria Gomezcanas, Ruth M Pazos, Javier Fernandezruiz, Battistina Asproni, Elena Cichero, Paola Fossa, Eduardo Munoz, Francesco Deligia, Gabriele Murineddu
    Abstract:

    Previous studies have investigated the relevance and structure-activity relationships (SARs) of pyrazole derivatives in relation with cannabinoid receptors, and the series of tricyclic 1,4-dihydroindeno[1,2-c]pyrazoles emerged as potent CB2 receptor ligands. In the present study, novel 1,4-dihydroindeno[1,2-c]pyrazole and 1H-benzo[g]indazole carboxamides containing a cyclopropyl or a cyclohexyl substituent were designed and synthesized to evaluate the influence of these structural modifications towards CB1 and CB2 receptor affinities. Among these derivatives, compound 15 (6-cyclopropyl-1-(2,4-dichlorophenyl)-N-(adamantan-1-yl)-1,4-dihydroindeno[1,2-c]pyrazole-3-carboxamide) showed the highest CB2 receptor affinity (Ki = 4 nM) and remarkable selectivity (KiCB1/KiCB2 = 2232), whereas a similar affinity, within the nM range, was seen for the fenchyl derivative (compound 10: Ki = 6 nM), for the bornyl analogue (compound 14: Ki = 38 nM) and, to a lesser extent, for the aminopiperidine derivative (compound 6: Ki = 69 nM). Compounds 10 and 14 were also highly selective for the CB2 receptor (KiCB1/KiCB2 > 1000), whereas compound 6 was relatively selective (KiCB1/KiCB2 = 27). The four compounds were also subjected to GTPγS binding analysis showing antagonist/inverse agonist properties (IC50 for compound 14 = 27 nM, for 15 = 51 nM, for 10 = 80 nM and for 6 = 294 nM), and this activity was confirmed for the three more active compounds in a CB2 receptor-specific in vitro bioassay consisting in the quantification of prostaglandin E2 release by LPS-stimulated BV2 cells, in the presence and absence of WIN55,212-2 and/or the investigated compounds. Modelling studies were also conducted with the four compounds, which conformed with the structural requirements stated for the binding of antagonist compounds to the human CB2 receptor.